1. Field of the Invention
The present invention relates to electronic circuits and systems. More specifically, the present invention relates to circuits and systems for compensating for the response of an automatic gain control amplifier for temperature and other effects.
2. Description f the Related Art
Automatic gain control (AGC) amplifiers are amplifiers which provide an output signal within a predetermined range notwithstanding significant variations in an input signal. AGC amplifiers are used in a wide variety of applications including communications, signal processing and the like.
It is well known in the art that response of AGC amplifiers can change as function of temperature. In certain applications, this temperature sensitivity is highly undesirable. For example, in a missile guidance application, an executive computer in a radio frequency (RF) seeker system may issue a digital command to control attenuation of AGC amplifiers in an intermediate frequency (IF) stage of the receiver. The command is converted to an analog voltage to drive the AGC amplifiers. The nonlinear, temperature sensitive response of the AGC amplifiers introduces an error which can adversely affect the accuracy of the missile.
Accordingly, compensation of AGC amplifier response to temperature has long been a desired feature. Traditional approaches have been to: 1) add temperature compensating elements to the amplifier and 2) measure temperature and compensate for its effects in software using a lookup table or an algorithm. The first approach adds expense and complexity to the amplifier design. The second approach adds an additional burden to a system processor and limits its throughput. Neither approach is easily tailored for individual production units.
Hence, a need remains in the art for a system or technique for effecting compensation of a circuit without requiring expensive circuit modifications or processing time.